Obtaining heeled waterlines in Freeship

[lewisboats]

This is from a post in the Design Forum but I think is useful enough to have it's own thread here. The essence of the post is here but the entire thread is "What's become of Plyboats?"




Well...with the meager tools at my disposal (Paint) and the obtainable views that I have been able to come up with so far...You CAN combine them up to a certain point...that point being that the centerline cannot be out of the water. DUH! If the centerline is out of the water then the rest of the hull is too...stupid!

Anyhoo...here is the result at 15 deg of heel...

http://www.angelfire.com/ego/lewisboatworks/Stuff/TiltCombined.JPG

The bottom is the windward side...the green is hull bottom out of the water, and the top is the lee side. Seems to work! It isn't perfect but it is pretty close...enough to give you an idea of what it would be at heeling angles


How I did this:
First...Save it as a different file! Then extrude the keel line up to the highest part of the boat to get the leakers above the waterline. DON'T do this AFTER rotating as you will be extruding at an angle to the hull! Deselect all then Transform/Rotate and rotate along the longitudinal axis...+ numbers will give you the lee side and - numbers will give you the windward side. The boat is going to rotate around the LCF so things are going to look a little weird in the bodyplan view. Deselect the Show control net button so the points disappear. Use the perspective view to get a plan view along the centerline looking down and right click and save image. Do the same, starting with the original and saving to another file name and tilt the hull in the opposite direction by the same amount. Open one file in your image editor of choice then flip, copy and open another copy of the editor with the other image, paste and line up the images.

Thank you Ancient WiseMan...for pointing me in the right direction! :D

Edited to add: you might want to fiddle with the color scheme to get the best results for seeing the waterlines

[frank smith]

nice but still dose not give heeled hydro info

[lewisboats]

Baby steps...Baby Steps...

[yipster]

i've also been heeling hulls in free delftship in another easy trick fashion that looked good but had no hydro results eighter tho

[lewisboats]

i've also been heeling hulls in free delftship in another easy trick fashion that looked good but had no hydro results eighter tho


Aaannnndddd....where are the pictures...the description of how to do it hmmmmm??...Weeeee're waaaaiting...(tap, tap , tap)

[yipster]

aii, before posting i did check free + delftship files but no... probably saved in another file and like the guy who asked their gone :rolleyes:
have to think how i did it, simple and good pics i recall, hmm.. later today i think + look again ( knew you would tap :D )

edit: ok found this and without redo it looks like i mirrored and rotated and it does give hydro, i just wasnt sure and still dont thrust its correct after the tricks
have to check into that again, as it would be very nice eh

here what i found

[frank smith]

I am ending up with some very strange catamarans

[lewisboats]

Thank you for that...so do you think you could give us a step by step when you have a chance to recreate what you did? If you mirror the hull half, does it automatically connect the two together or did you have to do something to it to have them joined? If you have the boat flat and level and it comes up with the same displacement as the original then...making a leap of faith...I would assume that heeling it and adjusting the waterline would provide the same results.

[yipster]

so do you think you could give us a step by step when you have a chance to recreate what you did?
really wanna hear all bout my late sixtys phycadelic san francisco nights?


looked again and dont think it can be done, i was after changing bottom profiles under heel and for that it was usefull

indeed very strange cats in lineplan and devellopment and altho i havent alzheiemer yet i dont recall how i did it
and doubt -even remember a thread (i think)- it can not be done in this program

do remember thinking of CFD or wat mitchlet would do with heeled hulls, hmm..

[frank smith]

load layers , mirror ,select all layers at prompt,mirror in vertical plan , rotate in vertical plane, adjust draft ,
get picture .

[frank smith]

I tried this , Mirrored the hull added new layers of mirror half , then moved boat off center line and mirrored it again , this gives you two boats . now delete one boat ,
and move other back to center , now rotate .

frank

[yipster]

frank, i didnt use layers but if you get the wanted result thats okay
geez, even forget now what it takes to place flowlines, button stays grey, hmm..
want to give these flowlines a try and see if the flow changes under heel?
see what the hydro does heeled and give us a call or look plz?

inventor, ansys, maxsurf AND delftship now calling and of all things i'm watching tv
affraid i''ll never going to be a good yacht designer..

[frank smith]

I think you can design a boat in you mind if that is all you have . I not to good with computer programs, nor do I have a great understanding of boat design .
Guess Ill have to trudge along best I can .

I use freeships to help in building a data base of a kind, and i like 3d views .
I am sure that if you wanted a simple boat that you could design it on freeships and and have the panels printed out , and build a boat from them.

Anyway, could not find any way to get heeled stability info out of freeships .
If there is a way it would be good to know about it

[yipster]

I think you can design a boat in you mind if that is all you have
i agree and delftship is a great way to visualise and obtain data on these fantasys
ok rtfm* again to check the flowlines button, they'r so nice and easy placed but will they show heeled flow?
frank, your hull must be closed to give hydrstatics, but compare results in heel
btw, maybe i only rotated and hope i did not scare lewis away :p

*read the fuckin manual ( but tricks as discussed here are not in it )

[frank smith]

if by flow lines you mean "diagonals", then you have to set it up using the
the icon show buttock ,waterlines ect.

I did not know there was a manual.

[yipster]

simple as pressing the Alt key to get those flowlines in but getting old i guess
here, -and hope jeff has enough terrabytes- the freeship 2.6 manual (again?) delftship manual is fatter and can be downloaded from delftship
look at page 39 for flowlines, almost fluid dynamics, gave it a try under heel but dont work in 5 min and probably wont, pitty, back to study the rest

[lewisboats]

Well, playing with it this morning I was able to get everything I was looking for...even flow lines. The hydrostatics adjusted themselves with the angle of heel too. All I did was turn on faces, selected all and mirrored, making sure that the little box that says connect to existing points is checked and voila...a sealed hull that can be tilted at will. Don't be confused by the body plan view...this will show what looks like two hulls...it is only the view from one end on one side and the other end on the other side...I thought I had messed up for a moment before I realized what I did. Tried it first on a symmetrical hull then something a little more like a cat boat hull...worked fine both ways

Here is the assym one:

http://www.angelfire.com/ego/lewisboatworks/Stuff/Saphire/SaphHullHeeled.JPG

Oh...if you have other layers that are deselected so you can see the waterlines...make sure when you rotate it that you check the little box about including points that are shared or you will lose some of your hull...or else rotate with everything visible then deselect your excess layers.

[yipster]

knew its a tough puppy from delft and good to see succes beyond the manual
your not saying you got the flowlines flowing a heeled flow too do you ?

[frank smith]

would you explain what flow lines are please.

Now for kicks I think you can rotate 180 and get the rear view heeled .
I also tried to rotate 90 and fool the program a little , it did not work .
but I am thinking that it might work with a section of the mid ship .
make the section 6" thick for start , heel, then rotate 90 , set left edge to 0
and add buttock lines . Probable only work for balanced DE hulls

[lewisboats]

Yes...got flow lines because you can only get the lines to work below the waterline...so anywhere on the hull that is submerged will be able to display flow lines. You can get rear view heeled by using the perspective window and rotating the hull to the correct position...it is almost there in the upper left window in the above screen capture.

Flow lines are the lines the water will supposedly take as it flows across the hull...not counting for leeway or any other effect...so useful in only a small way but useful still. Heeled buttock lines might give a better indication (yes they are available too, along with heeled everything else).
http://www.angelfire.com/ego/lewisboatworks/Stuff/Saphire/Flowlines.JPG

[daiquiri]

Great tool for the visualisation of heeled waterlines!
Too bad that Freeship goes nuts when you ask him to calculate the hydrostatics the hull heeled like that... :(

[lewisboats]

Where does it go nuts and please explain why it is nuts. I am especially curious about the negatives...for instance the entrance angle.

Here are the heeled hydros:

Project : Eagle14
Designer : Steven Lewis
Filename : D:\FreeShip\Designs\Saphire Alternate Heeled.fbm

Design length : 14.369 [ft]
Length over all : 14.000 [ft]
Design beam : 5.899 [ft]
Beam over all : 6.629 [ft]
Design draft : 0.725 [ft]
Midship location : 7.438 [ft]
Water density : 63.989 [lbs/ft3]
Appendage coefficient : 1.0000
Volume properties:
Displaced volume : 30.868 [ft3]
Displacement : 0.882 [tons]
Total length of submerged body : 13.244 [ft]
Total beam of submerged body : 5.286 [ft]
Block coefficient : 0.6082
Prismatic coefficient : 0.5596
Vert. prismatic coefficient : 0.5411
Wetted surface area : 87.843 [ft2]
Longitudinal center of buoyancy : 6.716 [ft]
Longitudinal center of buoyancy : -5.448 [%]
Vertical center of buoyancy : 0.475 [ft]
Midship properties:
Midship section area : 4.165 [ft2]
Midship coefficient : 1.0867
Waterplane properties:
Length on waterline : 13.244 [ft]
Beam on waterline : 5.286 [ft]
Waterplane area : 78.678 [ft2]
Waterplane coefficient : 1.1239
Waterplane center of floatation : 6.377 [ft]
Entrance angle : -3.922 [degr.]
Transverse moment of inertia : 53.404 [ft4]
Longitudinal moment of inertia : -1225.9 [ft4]
Initial stability:
Transverse metacentric height : 2.205 [ft]
Longitudinal metacentric height : -39.240 [ft]
Lateral plane:
Lateral area : 5.694 [ft2]
Longitudinal center of effort : 7.480 [ft]
Vertical center of effort : 0.466 [ft]




The following layer properties are calculated for both sides of the ship:
| Layer | Area | Thickness | Weight | COG X | COG Y | COG Z |
| | [ft2] | | [tons] | [ft] | [ft] | [ft] |
|-------------------------|--------|-----------|----------|---------|---------|---------|
| Strake 1 | 81.202 | 0.750 | 0.070 | 5.744 | 0.000 | 0.425 |
| Strake 2 | 27.439 | 0.375 | 0.012 | 6.368 | 0.000 | 0.745 |
| Strake 3 | 112.45 | 0.250 | 0.032 | 7.556 | 0.000 | 1.817 |
| Close hull | 12.095 | 0.625 | 0.008 | 0.164 | 0.000 | 1.791 |
| Layer 5 | 31.884 | 0.250 | 0.009 | 9.392 | 0.000 | 3.220 |
| Layer 6 | 12.021 | 0.250 | 0.003 | 4.396 | 0.000 | 2.977 |
| Layer 7 | 34.008 | 0.250 | 0.010 | 9.091 | 0.000 | 3.761 |
|-------------------------|--------|-----------|----------|---------|---------|---------|
Total 311.10 0.145 6.327 0.000 1.298
NOTE 1: Draft (and all other vertical heights) is measured above the lowest point of the hull! (Z= -0.419)
NOTE 2: All calculated coefficients based on actual dimensions of submerged body.



and here are the unheeled hydros:


Project : Eagle14
Designer : Steven Lewis
Filename : D:\FreeShip\Designs\Saphire Alternate.fbm

Design length : 14.369 [ft]
Length over all : 14.000 [ft]
Design beam : 5.899 [ft]
Beam over all : 5.750 [ft]
Design draft : 0.725 [ft]
Midship location : 7.438 [ft]
Water density : 63.989 [lbs/ft3]
Appendage coefficient : 1.0000
Volume properties:
Displaced volume : 34.586 [ft3]
Displacement : 0.988 [tons]
Total length of submerged body : 13.622 [ft]
Total beam of submerged body : 4.841 [ft]
Block coefficient : 0.7234
Prismatic coefficient : 0.5397
Vert. prismatic coefficient : 0.5375
Wetted surface area : 97.077 [ft2]
Longitudinal center of buoyancy : 6.857 [ft]
Longitudinal center of buoyancy : -4.260 [%]
Vertical center of buoyancy : 0.485 [ft]
Midship properties:
Midship section area : 4.704 [ft2]
Midship coefficient : 1.3403
Waterplane properties:
Length on waterline : 13.622 [ft]
Beam on waterline : 4.841 [ft]
Waterplane area : 88.751 [ft2]
Waterplane coefficient : 1.3458
Waterplane center of floatation : 6.314 [ft]
Entrance angle : -2.042 [degr.]
Transverse moment of inertia : 60.420 [ft4]
Longitudinal moment of inertia : -1352.5 [ft4]
Initial stability:
Transverse metacentric height : 2.232 [ft]
Longitudinal metacentric height : -38.620 [ft]
Lateral plane:
Lateral area : 7.066 [ft2]
Longitudinal center of effort : 7.409 [ft]
Vertical center of effort : 0.425 [ft]




The following layer properties are calculated for both sides of the ship:
| Layer | Area | Thickness | Weight | COG X | COG Y | COG Z |
| | [ft2] | | [tons] | [ft] | [ft] | [ft] |
|-------------------------|--------|-----------|----------|---------|---------|---------|
| Strake 1 | 81.202 | 0.750 | 0.070 | 5.744 | 0.000 | 0.331 |
| Strake 2 | 27.439 | 0.375 | 0.012 | 6.368 | 0.000 | 0.657 |
| Strake 3 | 112.45 | 0.250 | 0.032 | 7.556 | 0.000 | 1.753 |
| Close hull | 12.095 | 0.625 | 0.008 | 0.164 | 0.000 | 1.727 |
| Layer 5 | 31.884 | 0.250 | 0.009 | 9.392 | 0.000 | 3.188 |
| Layer 6 | 12.021 | 0.250 | 0.003 | 4.396 | 0.000 | 2.939 |
| Layer 7 | 34.008 | 0.250 | 0.010 | 9.091 | 0.000 | 3.741 |
|-------------------------|--------|-----------|----------|---------|---------|---------|
Total 311.10 0.145 6.327 0.000 1.222
NOTE 1: Draft (and all other vertical heights) is measured above the lowest point of the hull! (Z= -0.324)
NOTE 2: All calculated coefficients based on actual dimensions of submerged body.




And finally the unadulterated unmirrored unheeled hull specs:

Project : Eagle14
Designer : Steven Lewis
Filename : D:\FreeShip\Designs\Saphire Alternate.fbm

Design length : 14.369 [ft]
Length over all : 14.000 [ft]
Design beam : 5.899 [ft]
Beam over all : 5.750 [ft]
Design draft : 0.725 [ft]
Midship location : 7.438 [ft]
Water density : 63.989 [lbs/ft3]
Appendage coefficient : 1.0000
Volume properties:
Displaced volume : 17.293 [ft3]
Displacement : 0.494 [tons]
Total length of submerged body : 13.622 [ft]
Total beam of submerged body : 4.841 [ft]
Block coefficient : 0.3617
Prismatic coefficient : 0.5397
Vert. prismatic coefficient : 0.5375
Wetted surface area : 48.538 [ft2]
Longitudinal center of buoyancy : 6.857 [ft]
Longitudinal center of buoyancy : -4.260 [%]
Vertical center of buoyancy : 0.485 [ft]
Midship properties:
Midship section area : 2.352 [ft2]
Midship coefficient : 0.6701
Waterplane properties:
Length on waterline : 13.622 [ft]
Beam on waterline : 4.841 [ft]
Waterplane area : 44.376 [ft2]
Waterplane coefficient : 0.6729
Waterplane center of floatation : 6.314 [ft]
Entrance angle : 21.037 [degr.]
Transverse moment of inertia : 60.419 [ft4]
Longitudinal moment of inertia : 416.50 [ft4]
Initial stability:
Transverse metacentric height : 3.979 [ft]
Longitudinal metacentric height : 24.570 [ft]
Lateral plane:
Lateral area : 7.066 [ft2]
Longitudinal center of effort : 7.409 [ft]
Vertical center of effort : 0.425 [ft]




The following layer properties are calculated for both sides of the ship:
| Layer | Area | Thickness | Weight | COG X | COG Y | COG Z |
| | [ft2] | | [tons] | [ft] | [ft] | [ft] |
|-------------------------|--------|-----------|----------|---------|---------|---------|
| Strake 1 | 40.601 | 0.750 | 0.035 | 5.744 | 0.000 | 0.331 |
| Strake 2 | 13.720 | 0.375 | 0.006 | 6.368 | 0.000 | 0.657 |
| Strake 3 | 56.224 | 0.250 | 0.016 | 7.556 | 0.000 | 1.753 |
| Close hull | 6.047 | 0.625 | 0.004 | 0.164 | 0.000 | 1.727 |
| Layer 5 | 15.942 | 0.250 | 0.005 | 9.392 | 0.000 | 3.188 |
| Layer 6 | 6.010 | 0.250 | 0.002 | 4.396 | 0.000 | 2.939 |
| Layer 7 | 16.999 | 0.250 | 0.005 | 9.089 | 0.000 | 3.741 |
|-------------------------|--------|-----------|----------|---------|---------|---------|
Total 155.54 0.072 6.327 0.000 1.222
NOTE 1: Draft (and all other vertical heights) is measured above the lowest point of the hull! (Z= -0.324)
NOTE 2: All calculated coefficients based on actual dimensions of submerged body.

[lewisboats]

Looking at them I can state that the unmirrored original hull's weight numbers are half what the mirrored hull's are...because the panels' surfaces are doubled...code error. If you halved the weight of the panel material it might just give the correct #s. Notice the COG Z did shift between the heeled hull and the unheeled hull. I will have to play with this a bit more to see if I can get around the obstacles. At a glance I see 3 problems with negative numbers...one of which, the entrance angle, has me baffled. Once mirrored the entrance angle goes to negative numbers but I can't figure out why.

[lewisboats]

Got better results by assigning each of the panels on the mirrored side to new layers, then excluding the layers from the hydrostatics but leaving the Symmetrical on. All numbers are back in on the positive side and in reasonable ranges. I halved the weights for each panel so the CGs should come out right too.

Here is the heeled version with the extra layers

Project : Eagle14
Designer : Steven Lewis
Filename : D:\FreeShip\Designs\Saphire Alternate Heeled.fbm

Design length : 14.369 [ft]
Length over all : 14.000 [ft]
Design beam : 5.899 [ft]
Beam over all : 6.629 [ft]
Design draft : 0.725 [ft]
Midship location : 7.438 [ft]
Water density : 63.989 [lbs/ft3]
Appendage coefficient : 1.0000
Volume properties:
Displaced volume : 23.641 [ft3]
Displacement : 0.675 [tons]
Total length of submerged body : 13.244 [ft]
Total beam of submerged body : 5.286 [ft]
Block coefficient : 0.4658
Prismatic coefficient : 0.5805
Vert. prismatic coefficient : 0.6282
Wetted surface area : 59.105 [ft2]
Longitudinal center of buoyancy : 6.524 [ft]
Longitudinal center of buoyancy : -6.899 [%]
Vertical center of buoyancy : 0.454 [ft]
Midship properties:
Midship section area : 3.075 [ft2]
Midship coefficient : 0.8024
Waterplane properties:
Length on waterline : 13.244 [ft]
Beam on waterline : 5.286 [ft]
Waterplane area : 51.904 [ft2]
Waterplane coefficient : 0.7414
Waterplane center of floatation : 6.054 [ft]
Entrance angle : 23.160 [degr.]
Transverse moment of inertia : 90.198 [ft4]
Longitudinal moment of inertia : 530.49 [ft4]
Initial stability:
Transverse metacentric height : 4.270 [ft]
Longitudinal metacentric height : 22.894 [ft]
Lateral plane:
Lateral area : 2.257 [ft2]
Longitudinal center of effort : 7.716 [ft]
Vertical center of effort : 0.292 [ft]




The following layer properties are calculated for both sides of the ship:
| Layer | Area | Thickness | Weight | COG X | COG Y | COG Z |
| | [ft2] | | [tons] | [ft] | [ft] | [ft] |
|-------------------------|--------|-----------|----------|---------|---------|---------|
| Strake 1 | 40.601 | 0.750 | 0.018 | 5.744 | 0.000 | 0.253 |
| Strake 2 | 13.720 | 0.375 | 0.003 | 6.368 | 0.000 | 0.393 |
| Strake 3 | 56.224 | 0.250 | 0.008 | 7.556 | 0.000 | 1.411 |
| Close hull | 6.047 | 0.625 | 0.002 | 0.164 | 0.000 | 1.603 |
| Layer 5 | 31.884 | 0.250 | 0.009 | 9.392 | 0.000 | 3.220 |
| Layer 6 | 12.021 | 0.250 | 0.003 | 4.396 | 0.000 | 2.977 |
| Layer 7 | 34.008 | 0.250 | 0.010 | 9.091 | 0.000 | 3.761 |
| Layer 8 | 40.601 | 0.000 | 0.000 | 5.744 | 0.000 | 0.598 |
| Layer 9 | 13.720 | 0.000 | 0.000 | 6.368 | 0.000 | 1.097 |
| Layer 10 | 56.224 | 0.000 | 0.000 | 7.556 | 0.000 | 2.223 |
| Layer 11 | 6.047 | 0.000 | 0.000 | 0.164 | 0.000 | 1.979 |
|-------------------------|--------|-----------|----------|---------|---------|---------|
Total 311.10 0.053 7.027 0.000 1.821
NOTE 1: Draft (and all other vertical heights) is measured above the lowest point of the hull! (Z= -0.419)
NOTE 2: All calculated coefficients based on actual dimensions of submerged body.

[lewisboats]

Notice the displacement went up... so to get an accurate reflection of the heeled hull...you would need to reduce the draft to get it back to the correct displacement...which would change your numbers significantly.

Here the draft was reduced from .75 feet to .596 to obtain the same displacement. Compare the numbers to the original unadulterated hull whilst I go beddy bye. I have to work in 4.5 hours. (they are pretty darn close IMHO)!

Project : Eagle14
Designer : Steven Lewis
Filename : D:\FreeShip\Designs\Saphire Alternate Heeled.fbm

Design length : 14.369 [ft]
Length over all : 14.000 [ft]
Design beam : 5.899 [ft]
Beam over all : 6.629 [ft]
Design draft : 0.596 [ft]
Midship location : 7.438 [ft]
Water density : 63.989 [lbs/ft3]
Appendage coefficient : 1.0000
Volume properties:
Displaced volume : 17.276 [ft3]
Displacement : 0.494 [tons]
Total length of submerged body : 12.233 [ft]
Total beam of submerged body : 5.167 [ft]
Block coefficient : 0.4584
Prismatic coefficient : 0.5774
Vert. prismatic coefficient : 0.6146
Wetted surface area : 52.438 [ft2]
Longitudinal center of buoyancy : 6.671 [ft]
Longitudinal center of buoyancy : -6.268 [%]
Vertical center of buoyancy : 0.378 [ft]
Midship properties:
Midship section area : 2.446 [ft2]
Midship coefficient : 0.7938
Waterplane properties:
Length on waterline : 12.233 [ft]
Beam on waterline : 5.167 [ft]
Waterplane area : 47.149 [ft2]
Waterplane coefficient : 0.7459
Waterplane center of floatation : 6.280 [ft]
Entrance angle : 28.101 [degr.]
Transverse moment of inertia : 79.594 [ft4]
Longitudinal moment of inertia : 413.34 [ft4]
Initial stability:
Transverse metacentric height : 4.986 [ft]
Longitudinal metacentric height : 24.304 [ft]
Lateral plane:
Lateral area : 2.257 [ft2]
Longitudinal center of effort : 7.716 [ft]
Vertical center of effort : 0.292 [ft]




The following layer properties are calculated for both sides of the ship:
| Layer | Area | Thickness | Weight | COG X | COG Y | COG Z |
| | [ft2] | | [tons] | [ft] | [ft] | [ft] |
|-------------------------|--------|-----------|----------|---------|---------|---------|
| Strake 1 | 40.601 | 0.750 | 0.018 | 5.744 | 0.000 | 0.253 |
| Strake 2 | 13.720 | 0.375 | 0.003 | 6.368 | 0.000 | 0.393 |
| Strake 3 | 56.224 | 0.250 | 0.008 | 7.556 | 0.000 | 1.411 |
| Close hull | 6.047 | 0.625 | 0.002 | 0.164 | 0.000 | 1.603 |
| Layer 5 | 31.884 | 0.250 | 0.009 | 9.392 | 0.000 | 3.220 |
| Layer 6 | 12.021 | 0.250 | 0.003 | 4.396 | 0.000 | 2.977 |
| Layer 7 | 34.008 | 0.250 | 0.010 | 9.091 | 0.000 | 3.761 |
| Layer 8 | 40.601 | 0.000 | 0.000 | 5.744 | 0.000 | 0.598 |
| Layer 9 | 13.720 | 0.000 | 0.000 | 6.368 | 0.000 | 1.097 |
| Layer 10 | 56.224 | 0.000 | 0.000 | 7.556 | 0.000 | 2.223 |
| Layer 11 | 6.047 | 0.000 | 0.000 | 0.164 | 0.000 | 1.979 |
|-------------------------|--------|-----------|----------|---------|---------|---------|
Total 311.10 0.053 7.027 0.000 1.821
NOTE 1: Draft (and all other vertical heights) is measured above the lowest point of the hull! (Z= -0.419)
NOTE 2: All calculated coefficients based on actual dimensions of submerged body.

[daiquiri]

Where does it go nuts and please explain why it is nuts.
Well, you've asked a question and you gave the answer immediately afterwards. ;)
That's why I said that he FS goes nuts with heeled hull hydrostatics.
I hope Viktor is reading this thread, he can probably figure out why does it behave in such way...
I will PM him and ask if can take a look at that stuff. Though I'm aware that he is doing it for free (in his spare time?), so we cannot pretend an immediate reply...

[frank smith]

If freeships works on half hull measurements then the position of the cob is going to throw it off if not over the center line . btw when rotating the boat what is the location of the axis?

frank

[lewisboats]

0 on location of axis and Freeship only lists the Longitudinal center of buoyancy not the transverse one so the position should only move along the Longitudinal axis which it apparently does.

[frank smith]

so how will you know what the transverse cob location would be? Would'nt this
effect most of the calculations of heeled disp. and the like ?

[lewisboats]

Don't know...I'm still just working all this out...give me a bit of a chance. I'm just popping into the house between jobs. I'll have to wait until morning until I can do more exploring. Hopefully Martjin will pop in and give us some words of wisdom

[daiquiri]

Yep... It would be nice if Martjin could think it over too, because Delftship is most probably behaving in a same manner. They appear to run on the same graphics and a similar math engine.

[yipster]

dont really know what bugged him out but if Martijn say's hello here again i'll pay my last but long overdue 50.- share for the program rite now

[lewisboats]

Oh...he's around...just not every day or in every thread. I think he checks in once a week or so.

[Martijn_vE]

Hi Guys,

To jump in straight away, the orginal FREE!ship code was not setup for asymmetrical hulls, (or symmetrical hulls in a heeled condition). As some of you might remember the project was heavily under development. Still, this work around is quite ingenius and should work, even in FREE!ship. The longitudinal center of buoyancy is displayed along with the VCB. TCB is also calculated if I remember correctly. I'm sure Victor would be willing enough to include it in the output.

If you send me the file Lewis, I can run it through DELFTship as a benchmark.

[Martijn_vE]

By the way Steve,

You design reminded me of Bolger. I just found out about him the other day. Really, really sad.......
But then again, he wasn't really a conventional type of guy....

[lewisboats]

Morning...after doing a bit of research into my books to look up for the correct formula...determining the righting arm from the available data appears to be relatively easy. Hopefully my math is up to the task.

First...heeled displacement is a factor of draft...and is given in the displacement portion of the data. To adjust the displacement at heel (which should match the displacement at rest...just 'cause it leans over doesn't mean it gets any fatter) you will need to play with the draft until you get the correct displacement. I recommend you save many iterations of the hull at different angles of heel and with corrected drafts to get an overall picture at the same displacement.

To determine the righting arm at a specific angle of heel take the Transverse Metacentric height and multiply it by the Sin of the angle in degrees. This should give the length of the righting arm. Then multiply that result by the displacement. To get foot lbs (for working with smaller boats) multiply this by the number of lbs in the selected displacement unit (2240 lbs/ton in the imperial measure) to get foot/lbs. If you want Newton/metres or something else you are on your own ;).

[lewisboats]

If you send me the file Lewis, I can run it through DELFTship as a benchmark.

Cross post!

Sure...no problem. You know...I just noticed I have been spelling your log in wrong for....ever...sorry 'bout that :(

First name is Martin right?

Steve Lewis

PS: TCB is not included but If I got things right is easily calculated using the GM, the angle of heel and the displacement.

PPS: Check your PMs

[Martijn_vE]

You know...I just noticed I have been spelling your log in wrong for....ever...sorry 'bout that :(
First name is Martin right?

Actually it's Martijn, but don't worry, I listen to a lot of names, most of which are meant in a good way.

Anyway, GM can only be used up to a small (say 8 degrees) heeling angle. The exact measure for transverse stability, the righting arm, is simply the horizontal distance between the center of gravity and transverse center of buoyancy. So not GM but TCB is what you really need.

[lewisboats]

Aha! I found a paper which gave the formula GZ=GM (sin X) where X is the degrees of heel. They did mention that up to about 10 deg you could sub (X/57,3) for (Sin X) so this is what I used for the above. Guess I'll only build boats that heel to 8 deg then LOL

Steve

[Martijn_vE]

Steve,

I had to move the boat up a bit so the lowest point coincides with the base plane. I hope the draught and displacement are still correct.

Here's what DELFTship came up with:
(Notice also the small difference in upright and heeled sectional area curves of the 3rd image, the design is very close to trim neutral at this angle of inclination)

[lewisboats]

Steve,

I had to move the boat up a bit so the lowest point coincides with the base plane. I hope the draught and displacement are still correct.

Here's what DELFTship came up with:

Actually the draft listed in the file you got should be .75 ft or 9 inches and displacement of .882 tons. I forgot to save the last iteration where I had corrected the draft and disp to match the unmirrored original hull. I will re-upload the file in a moment so if you hit the link it will give you the correct file. Give me about 2 minutes

[lewisboats]

File uploaded. It should have a draft of .531 and a displacement of .494 tons which is the design displacement for the hull

Steve

[lewisboats]

(Notice also the small difference in upright and heeled sectional area curves of the 3rd image, the design is very close to trim neutral at this angle of inclination)

I take it that that is a GOOD thing? I assume that it means the hull shape at this angle of heel is still fairly balanced and the helm won't be very affected.

Steve

Edited to add: no...sounds like the boat hasn't pitched any significant amount as it heeled to that angle.

[Martijn_vE]

I take it that that is a GOOD thing?
Yep.
Have a look at the stability report.
You can see that up to 15 degrees of heel there's almost nu change in trim.
Most yachts with a a large beam (and wide transom modern yachts too) tend to dive down with the bow, and lifting the rudder out of the water.
Yours seems just fine.

I only have a displacement of 0.526 tons at .75 foot of draft though.....

[Martijn_vE]

It seems that you keep your feet dry until 59 degrees of heel.
After that it's over.....

[lewisboats]

Well...none of the interior stuff is there...it has a the standard cockpit layout with a bench on each side and the cabin hatch/companion way in the middle. I expect it to reach at least 110 degrees before it tries to go all the way over. The cockpit is self draining so if the cabin entryway is sealed properly it should drain itself if and when you get it back upright.

[Martijn_vE]

What I was merely trying to say is that the boat is dry until 59 degrees, after that water enters the cockpit. It's not necessarily the end of your boat.

[lewisboats]

Oh...I know...no problems. I didn't give you the file with the interior so I was trying to explain what I had in mind. It was only after I read your post that I saw you had posted in the Plyboats thread and had thus probably seen the interior and cockpit layout. I haven't tried to mirror that one yet.

[yipster]

really nice that these things are possible with free / delftship also and hear Martijn on his program again
i'll pay my last but long overdue 50.- share for the program rite now
forgot, but thought 50.- was discussed once as share in teh devellopment of free!ship if we liked it

[yipster]

well 35000x50 wont work i guess and buying some dellicious dutch chinese food tonight then i must thank you Steve and Martijn for your posts
so taking care all this is fairly easy possible, altho still having some doubles in the flowlines too, its more fun than studying inventor

[frank smith]

it must take a lot of HP to get that hull to plane at that angle .

[lewisboats]

Looks to me like you have your quality too low...that might be part of the problem...try changing to highest (in Freeship).

[Martijn_vE]

it must take a lot of HP to get that hull to plane at that angle .

That or a really heavy person sitting on the transom, taking the draft into account:D

[yipster]

Martijn, i'm not trying to spoil the tread but what to think or reply?
draft as in design, boat, payment, or a simple joke? i use free!ship for pleasure and think of it as a great gift ( or was it shareware )
and did not mean to insult you, like to see devellopment but dont like copy's sold eighter
i refer to the manual for flowline use but shown hull was only a quik test on a non linear hull giving it some pitch and yaw to see if it works this way too
witch it seems to do to an extend, quality is on and the shadowing, i think, is the result of the hidden second hulls geometry, as are some lines, havent figgered it out
for all boat lovers having dinner, bon appetit, live is good, taxes just aint :-(
ps had a volvo shakespere speedboat once that was actually good making that angle going WOT

[Martijn_vE]

Don't worry Joop, it was simply a joke. I noticed that the DWL was very high, and I assumed this was done simply to play with the flowlines. Did not mean to offend you at all.

[yipster]

thanks Martijn, you even got my dutch unspeakable in english nickname
i owe you one and "eet smakelijk" :D

[Martijn_vE]

thanks Martijn, you even got my dutch unspeakable in english nickname
I figure that would be "djoep", or something alike.
The only thing I don't understand was your remark about selling copies.
Are you referring to FREE!ship or DELFTship here?

[daiquiri]

Maybe I have missed something here, also because the solution seem to be spread over several posts...
So please, can someone write here a 10-lines (or as many as you need...) primer on how do you guys obtain hydrostatic properties of a heeled hull, either with Freeship or with Delftship?
Here is an example of a sailboat hull, let's say we want to heel it to 20°.

[lewisboats]

That's because the solution was developed over several posts...progress reports so to speak :D

Seeing as I can't open it 'cause it is a later version than what I have I'll have to punt

I am assuming it is a half hull and not mirrored yet.
1: Save the file to something else so you don't mess up the original.
2: Select all then go to Transform/Mirror...you are going to mirror on the vertical plane, distance 0 and connect to existing points should be checked. Click OK.
3: Deselect all and then make a new layer. Click the Show interior edges button to turn on the mesh. Start putting the MIRRORED stuff on separate layers. Once you have done that go into the layers properties and for all the layers of the MIRRORED side deselect the "Use for hydrostatics" box but leave the symmetric box checked. Got to Calcs/design hydrostatics and copy all the info so you can compare...paste to a .txt file.
4: Got to Transform/rotate and rotate along the longitudinal axis and put in your degree amount that you wish to rotate the hull. + numbers rotate to port and - numbers rotate starboard.
5: Check your hydrostatics...then adjust your DRAFT so that you get your Displacement back to what it was in the unrotated info (your .txt file) or your previous unmirrored model. You will have to fiddle with the draft to return to your proper displacement each time you change the heel angle.

You should now have the info you are looking for.

[lewisboats]

In the above...all of your surface areas will be doubled...can't seem to get away from that...so you will need to reduce your thickness by half or your weights per thickness (provided you already have put something in there of course)

[Martijn_vE]

Close you hull on the centerline, see first image
Mirror in the centerplane, see second image (do NOT connect to already existing points!
Rotate 20 degrees around the longitudinal axis, image 3
Finally turn of the symmetry property of your hull layers, so the calculated volume is not doubled automaticaaly anymore since you have the hull modeled on both sides already

[lewisboats]

Why do you need to close the centerline?...works fine without doing that and connecting the points. You're right about the symmetric part though. Thnx for the catch.

[Martijn_vE]

Why do you need to close the centerline?...works fine without doing that and connecting the points.
Ahh, beaten at my own game.....:(

[lewisboats]

Nah! you're playing by the rules that you wrote...I just like to bend them till they break....

[daiquiri]

And how do you disable "symmetric" option without disabling "use for hydrostatics" option too?

[lewisboats]

And how do you disable "symmetric" option without disabling "use for hydrostatics" option too?

You do both...you don't need it as the program is already doubling everything to cover both sides.

[yipster]

only thing I don't understand was your remark about selling copies.
Are you referring to FREE!ship or DELFTship here?
from other threads i remember foreign copy cat selling your stuff
tomorrow i try above's, hydro's too, thanks

djoep

works fine, does keel and rudder wizzard too and looks great!